Continuous evaluation of yarn crimp

ABSTRACT

Yarn is caused to travel at a velocity w1 under a constant tension sufficient to straighten but insufficient to stretch the yarn. Downstream of the point of application of this tension, a second constant tension is applied to the yarn, the second tension being small enough to allow any crimp in the yarn to be re-formed. The velocity w2 of the yarn traveling past the point of application of the second constant tension is continuously measured, and the crimp along the length of the yarn is continuously evaluated by means of the relationship



1. A continuous process for evaluation of the crimp along the length of a yarn, which process comprises the following sequential steps: a. Causing the yarn to travel at a velocity w1 under a constant tension sufficient to straighten but not substantially stretch the yarn, and continuously measuring velocity w1; b. Subjecting the traveling yarn, at a point downstream of the application of the first constant tension, to a second constant tension which is small enough to allow any crimp in the yarn to be re-formed; c. Continuously measuring the velocity w2 of the yarn as it travels past the point of application of the second constant tension; and d. Continuously evaluating the crimp along the length of the yarn by means of the relationship Crimp % ((w1-w2)/w1)
 100. 2. The process according to claim 1, wherein the yarn is subjected to an environment which affords the development of any latent crimp in the yarn between the points where tension is applied to the yarn.
 3. A device for the continuous evaluation of crimp along the length of a yarn, which device comprises: a. Means for causing the yarn to travel along a path at a velocity w1 under a constant tension sufficient to straighten but not substantially stretch the yarn; b. Means along said path for continuously measuring the velocity w1; c. Means for subjecting the traveling yarn, at a point downstream of the application of the first constant tension to a second constant tension small enough to allow crimp in the yarn to be re-formed; d. Means for continuously measuring the velocity w2 of the yarn traveling past the point of application of the second constant tension; and e. Means for continuously computing crimp along the length of the yarn utilizing the relationship Crimp (%) ((w1-w2)/w1)
 100. 4. A device according to claim 3, including means for developing latent crimp in the yarn between the points where tension is applied to the yarn. 